The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Deborah Moll - One of the best experts on this subject based on the ideXlab platform.
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a review of Nitrates in drinking water maternal exposure and adverse reproductive and developmental outcomes
Ciencia & Saude Coletiva, 2007Co-Authors: Deana M Manassaram, Lorraine C Backer, Deborah MollAbstract:In this review, we present an update on maternal exposure to Nitrates in drinking water in relation to possible adverse reproductive and developmental effects, and discuss Nitrates in drinking water in the United States. The current standard for Nitrates in drinking water is based on retrospective studies and approximates a level that protects infants from methemoglobinemia, but no safety factor is built into the standard. The current standard applies only to public water systems. Animal studies have found adverse reproductive effects resulting from higher doses of nitrate or nitrite. The epidemiologic evidence of a direct exposure-response relationship between drinking water nitrate level and adverse reproductive effect is still not clear. However, some reports have suggested an association between exposure to Nitrates in drinking water and spontaneous abortions, intrauterine growth restriction, and various birth defects. Uncertainties in epidemiologic studies include the lack of individual exposure assessment that would rule out confounding of the exposure with some other cause. We conclude that the current literature does not provide sufficient evidence of a causal relationship between exposure to Nitrates in drinking water and adverse reproductive effects.
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a review of Nitrates in drinking water maternal exposure and adverse reproductive and developmental outcomes
Environmental Health Perspectives, 2006Co-Authors: Deana M Manassaram, Lorraine C Backer, Deborah MollAbstract:In this review we present an update on maternal exposure to Nitrates in drinking water in relation to possible adverse reproductive and developmental effects, and also discuss Nitrates in drinking water in the United States. The current standard for Nitrates in drinking water is based on retrospective studies and approximates a level that protects infants from methemoglobinemia, but no safety factor is built into the standard. The current standard applies only to public water systems. Drinking water source was related to nitrate exposure (i.e., private systems water was more likely than community system water to have nitrate levels above the maximum contaminant limit). Animal studies have found adverse reproductive effects resulting from higher doses of nitrate or nitrite. The epidemiologic evidence of a direct exposure–response relationship between drinking water nitrate level and adverse reproductive effect is still not clear. However, some reports have suggested an association between exposure to Nitrates in drinking water and spontaneous abortions, intrauterine growth restriction, and various birth defects. Uncertainties in epidemiologic studies include the lack of individual exposure assessment that would rule out confounding of the exposure with some other cause. Nitrates may be just one of the contaminants in drinking water contributing to adverse outcomes. We conclude that the current literature does not provide sufficient evidence of a causal relationship between exposure to Nitrates in drinking water and adverse reproductive effects. Future studies incorporating individual exposure assessment about users of private wells—the population most at risk—should be considered.
E Bassenge - One of the best experts on this subject based on the ideXlab platform.
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comparison of glyceryl trinitrate induced with pentaerythrityl tetranitrate induced in vivo formation of superoxide radicals effect of vitamin c
Free Radical Biology and Medicine, 1999Co-Authors: Sergey Dikalov, Bruno Fink, M Skatchkov, E BassengeAbstract:Abstract Glyceryl trinitrate (GTN) and pentaerythrityl tetranitrate (PETN) are among the most known organic Nitrates that are used in cardiovascular therapy as vasodilators. However, anti-ischemic therapy with organic Nitrates is complicated by the induction of nitrate tolerance. When Nitrates are metabolized to release nitric oxide (NO), there is considerable coproduction of superoxide radicals in vessels leading to inactivation of NO. However, nitrate-induced increase of superoxide radical formation in vivo has not been reported. In this work, the authors studied the in vivo formation of superoxide radicals induced by treatment with PETN or GTN and determined the antioxidant effect of vitamin C. The formation of superoxide radicals was determined by the oxidation of 1-hydroxy-3-carboxy-pyrrolidine (CP-H) to paramagnetic 3-carboxy-proxyl (CP) using electron spin resonance spectroscopy. CP-H (9 mg/kg intravenous bolus and 0.225 mg/kg per minute continuous intravenous GTN or PETN 130 μg/kg) were infused into anesthetized rabbits. Every 5 min, blood samples were obtained from Arteria carotis to measure the CP formation. Both PETN and GTN showed similar vasodilator effects. Formation of CP in blood after infusions of GTN and PETN were 2.0 ± 0.4 μM and 0.98 ± 0.23 μM, respectively. Pretreatment with 30 mg/kg vitamin C led to a significant decrease in CP formation: 0.27 ± 0.14 μM (vitamin C plus GTN) and 0.34 ± 0.15 μM (vitamin C plus PETN). Pretreatment of animals with superoxide dismutase (15,000 units/kg) significantly inhibited nitrate-induced nitroxide formation. Therefore, in vivo infusion of GTN or PETN in rabbits increased the formation of superoxide radicals in the vasculature. PETN provoked a minimal stimulation of superoxide radical formation without simultaneous development of nitrate tolerance. The data suggest that the formation of superoxide radicals induced by organic nitrate correlates with the development of nitrate tolerance. The effect of vitamin C on CP formation leads to the conclusion that vitamin C can be used as an effective antioxidant for protection against nitrate-induced superoxide radical formation in vivo.
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formation of reactive oxygen species by pentaerithrityltetranitrate and glyceryl trinitrate in vitro and development of nitrate tolerance
Journal of Pharmacology and Experimental Therapeutics, 1998Co-Authors: Sergey Dikalov, Bruno Fink, M Skatchkov, D Stalleicken, E BassengeAbstract:Anti-ischemic therapy with organic Nitrates is complicated by tolerance. Induction of tolerance is incompletely understood and likely multifactorial. Recently, increased production of reactive oxygen species (ROS) has been investigated, but it has not been clear if this is a direct consequence of the organic nitrate on the vessel or an in vivo adaptation to the drugs. To examine the possibility that Nitrates could directly stimulate vascular ROS production, we compared the development of nitrate tolerance with the formation of ROS induced by pentaerithrityltetranitrate (PETN) or nitroglycerin (GTN) in vitro in porcine smooth muscle cells, endothelial cells, washed ex vivo platelets and whole blood. By examining cGMP formation, it was found that 24-hr treatment with GTN but not PETN induced significant nitrate tolerance, which was prevented by parallel treatment with Vit C. Incubation of vascular cells acutely with 0.5 mM GTN doubled the rate of ROS generation, whereas PETN had no such effect. The rate of ROS (peroxynitrite and O 2 —˙ ) formation detected by specific spin traps in tolerant smooth muscle cells, treated for 24 hr with 0.01 mM GTN, was substantially higher (30.5 nM/min) than in control cells acutely treated with 0.5 mM GTN (25 nM/min). In contrast to PETN, GTN induces nitrate tolerance and also increases the formation of ROS both in vascular cells and in whole blood. ROS formation is minimally stimulated by PETN comparable to data obtained in Vit C-suppressed GTN tolerance. ROS formation induced by organic Nitrates seems to be a key factor in the development of nitrate tolerance.
Deana M Manassaram - One of the best experts on this subject based on the ideXlab platform.
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a review of Nitrates in drinking water maternal exposure and adverse reproductive and developmental outcomes
Ciencia & Saude Coletiva, 2007Co-Authors: Deana M Manassaram, Lorraine C Backer, Deborah MollAbstract:In this review, we present an update on maternal exposure to Nitrates in drinking water in relation to possible adverse reproductive and developmental effects, and discuss Nitrates in drinking water in the United States. The current standard for Nitrates in drinking water is based on retrospective studies and approximates a level that protects infants from methemoglobinemia, but no safety factor is built into the standard. The current standard applies only to public water systems. Animal studies have found adverse reproductive effects resulting from higher doses of nitrate or nitrite. The epidemiologic evidence of a direct exposure-response relationship between drinking water nitrate level and adverse reproductive effect is still not clear. However, some reports have suggested an association between exposure to Nitrates in drinking water and spontaneous abortions, intrauterine growth restriction, and various birth defects. Uncertainties in epidemiologic studies include the lack of individual exposure assessment that would rule out confounding of the exposure with some other cause. We conclude that the current literature does not provide sufficient evidence of a causal relationship between exposure to Nitrates in drinking water and adverse reproductive effects.
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a review of Nitrates in drinking water maternal exposure and adverse reproductive and developmental outcomes
Environmental Health Perspectives, 2006Co-Authors: Deana M Manassaram, Lorraine C Backer, Deborah MollAbstract:In this review we present an update on maternal exposure to Nitrates in drinking water in relation to possible adverse reproductive and developmental effects, and also discuss Nitrates in drinking water in the United States. The current standard for Nitrates in drinking water is based on retrospective studies and approximates a level that protects infants from methemoglobinemia, but no safety factor is built into the standard. The current standard applies only to public water systems. Drinking water source was related to nitrate exposure (i.e., private systems water was more likely than community system water to have nitrate levels above the maximum contaminant limit). Animal studies have found adverse reproductive effects resulting from higher doses of nitrate or nitrite. The epidemiologic evidence of a direct exposure–response relationship between drinking water nitrate level and adverse reproductive effect is still not clear. However, some reports have suggested an association between exposure to Nitrates in drinking water and spontaneous abortions, intrauterine growth restriction, and various birth defects. Uncertainties in epidemiologic studies include the lack of individual exposure assessment that would rule out confounding of the exposure with some other cause. Nitrates may be just one of the contaminants in drinking water contributing to adverse outcomes. We conclude that the current literature does not provide sufficient evidence of a causal relationship between exposure to Nitrates in drinking water and adverse reproductive effects. Future studies incorporating individual exposure assessment about users of private wells—the population most at risk—should be considered.
Lars E. Gustafsson - One of the best experts on this subject based on the ideXlab platform.
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Direct demonstration of no formation in vivo from organic nitrites and Nitrates, and correlation to effects on blood pressure and to in vitro effects
Biochemical Pharmacology, 1994Co-Authors: Bo Cederqvist, Magnus G. Persson, Lars E. GustafssonAbstract:Previous studies, utilizing nitric oxide synthase inhibitors and nitric oxide application, indicate that nitric oxide has the capacity to modulate contractile responses in pulmonary vessels. In the present study, in vitro effects of organic Nitrates/nitrites were compared with their in vivo ability to generate nitric oxide and their effects on blood pressure. Glyceryl trinitrate, ethyl nitrite, isobutyl nitrate, isobutyl nitrite, isoamyl nitrite and butyl nitrite inhibited contractions in response to nerve stimulation in guinea pig pulmonary artery and vas deferens. Glyceryl trinitrate (also known as nitroglycerin) was the most potent and isobutyl nitrate the least potent substance with this action (ic50 4.5 ?? 0.2 ?? 10-10 and 1.1 ?? 0.1 ?? 10-5M, respectively). Contractile responses to noradrenaline were inhibited, whereas noradrenaline release was unaffected by organoNitrates/nitrites, indicating a post-junctional inhibitory effect. When infused intravenously to anaesthetized rabbits glyceryl trinitrate, ethyl nitrite and isobutyl nitrate generated dose-dependent increments of nitric oxide in exhaled air and dose-dependent decrements in systemic blood pressure. Significant correlations were obtained between in vivo NO generation and effects on blood pressure, as well as between NO generation in vivo and the in vitro activity of the organic nitrites and organic Nitrates. In conclusion, organic nitrites and organic Nitrates can modulate adrenergic neuroeffector transmission in guinea pig pulmonary artery and vas deferens, and produce detectable concentrations of nitric oxide in exhaled air in vivo, in the rabbit. The observations give direct in vivo evidence that organic nitrites and Nitrates generate NO, and strongly support them exerting their action via NO formation. ?? 1994.
Lorraine C Backer - One of the best experts on this subject based on the ideXlab platform.
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a review of Nitrates in drinking water maternal exposure and adverse reproductive and developmental outcomes
Ciencia & Saude Coletiva, 2007Co-Authors: Deana M Manassaram, Lorraine C Backer, Deborah MollAbstract:In this review, we present an update on maternal exposure to Nitrates in drinking water in relation to possible adverse reproductive and developmental effects, and discuss Nitrates in drinking water in the United States. The current standard for Nitrates in drinking water is based on retrospective studies and approximates a level that protects infants from methemoglobinemia, but no safety factor is built into the standard. The current standard applies only to public water systems. Animal studies have found adverse reproductive effects resulting from higher doses of nitrate or nitrite. The epidemiologic evidence of a direct exposure-response relationship between drinking water nitrate level and adverse reproductive effect is still not clear. However, some reports have suggested an association between exposure to Nitrates in drinking water and spontaneous abortions, intrauterine growth restriction, and various birth defects. Uncertainties in epidemiologic studies include the lack of individual exposure assessment that would rule out confounding of the exposure with some other cause. We conclude that the current literature does not provide sufficient evidence of a causal relationship between exposure to Nitrates in drinking water and adverse reproductive effects.
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a review of Nitrates in drinking water maternal exposure and adverse reproductive and developmental outcomes
Environmental Health Perspectives, 2006Co-Authors: Deana M Manassaram, Lorraine C Backer, Deborah MollAbstract:In this review we present an update on maternal exposure to Nitrates in drinking water in relation to possible adverse reproductive and developmental effects, and also discuss Nitrates in drinking water in the United States. The current standard for Nitrates in drinking water is based on retrospective studies and approximates a level that protects infants from methemoglobinemia, but no safety factor is built into the standard. The current standard applies only to public water systems. Drinking water source was related to nitrate exposure (i.e., private systems water was more likely than community system water to have nitrate levels above the maximum contaminant limit). Animal studies have found adverse reproductive effects resulting from higher doses of nitrate or nitrite. The epidemiologic evidence of a direct exposure–response relationship between drinking water nitrate level and adverse reproductive effect is still not clear. However, some reports have suggested an association between exposure to Nitrates in drinking water and spontaneous abortions, intrauterine growth restriction, and various birth defects. Uncertainties in epidemiologic studies include the lack of individual exposure assessment that would rule out confounding of the exposure with some other cause. Nitrates may be just one of the contaminants in drinking water contributing to adverse outcomes. We conclude that the current literature does not provide sufficient evidence of a causal relationship between exposure to Nitrates in drinking water and adverse reproductive effects. Future studies incorporating individual exposure assessment about users of private wells—the population most at risk—should be considered.
